Peptide Bond: Definition, Formation & Structure

Instructor: John Williams
Peptide bonds are the key linkages found in proteins. These bonds connect amino acids and provide one of the key foundations for protein structure. This article discusses peptide bonds, their formation, and their structure.


Proteins are a class of macromolecules (large molecules) that are important in biological systems. Almost all of the components of an organism will contain one or more types of protein in order to function properly. Your hair, for example, contains keratin, which is a protein used to make each strand. Your skin, likewise, contains proteins such as collagen, which is used to allow stretching. In addition to this, many of the biological systems require proteins for biochemical processes. For example, in muscle, proteins are responsible for contraction and energy usage. In the stomach, protein enzymes , which are biological catalysts, speed up the process of food digestion. In essence, proteins are vital for survival.

Proteins are formed from amino acids, which are the building blocks for this particular macromolecule. Amino acids are joined together in a process known as polymerization, which is where large molecules are produced by combining smaller units. Polymerization is achieved by the formation of special bonds known as peptide bonds.

Key Components of Amino Acids

Every amino acid will have two key chemical groups: an amine group and a carboxyl group. Amine groups are composed of one nitrogen and two hydrogen atoms (-NH2). Carboxyl groups contain one carbon double bonded to an oxygen and single bonded to a hydroxyl (-OH) group. These two groups form the foundation of for peptide bonds, and are seen in the generic amino acid shown below.

Generic Amino Acid: Amine and Carboxyl Groups
amino acid

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